Each year over 2 million adolescents are arrested in the U.S.[4], and many more (9-18 percent of all youth) engage in serious delinquent behavior, such as heavy drinking, illicit drug use, and school drop-out[5]. The most effective interventions to address these problems are family-based, with a strong clinical emphasis on helping parents regain control of youth behavior through better monitoring of activities and consistent use of contingencies (rewards and punishments) for appropriate and deviant behavior[6]. The fact that 21st century youth are technologically wired (75 percent now own a cell phone[1], spending an average of 33 minutes talking and 1.5 hours texting each day;[2] in addition, 93 percent of households with children now have Internet access[45]) offers an opportunity for parents to monitor youth more accurately and to provide more frequent, contingent rewards for good behavior than previously possible. The primary aim of this application is to develop and evaluate a sophisticated multi-component technology suite designed to enhance parents' ability to manage youth behavior. At the core of this VillageWhere suite is a mobile phone app for youth cell phones that uses contextual intelligence (notifies parents of youth activities and prompts youth to change behavior) and gamification (rewards youth and maintains youth engagement). The app will integrate with an Internet-based dashboard for parents (www.villagewhere.com) that will show youth whereabouts and consolidate information critical for parental management. This suite will be developed within the context of Multisystemic Therapy (MST), an empirically-supported and widely-disseminated intervention for youth antisocial behavior designed for the most serious subset of the target population. When incorporated into interventions such as MST, VillageWhere could enhance clinical outcomes while reducing treatment length and cost and expanding treatment access. We will use an iterative development process involving feedback from end-users during all stages of prototype development. Given the novelty of VillageWhere, in Phase I we will conduct an extensive formative evaluation to confirm and ensure proof of concept, and a summative evaluation to examine the product's usability, acceptability, and feasibility. Throughout Phase I we will gather in-depth qualitative and quantitative data from parents, youth, and clinicians drawn from an extensive network of MST providers. In the event of a successful Phase I formative evaluation, we will propose a Phase II plan to conduct a between subjects RCT comparing the fully completed VillageWhere system delivered within MST to MST as usual and examine a range of youth-, parent-, and therapist-level outcomes.